Trimming excess on loft

Hello all

I have two problems that are giving me a hard time.

How can i automaticly trim excess of this colums, so it extrude only to the loft.

And is there smarter way to do this, my object goes into negative coordinates, can i extend columns both side with one command or do i have to do it like i did here with one Unit Z vector in negative, and other into positive direction

Thank you
Rap (32.5 KB)

You’ve forgotten to internalise your data!

Sorry im New on Grasshopper, what does that mean?